Since my greatest fear on a long ride is going hungry I will eat pretty close to the start of the ride (like an hour); but if it's a shorter ride I'll try not to eat less than 2.5 hours before so that I can ride harder (I don't want to be digesting). Since I have a hard time not riding hard, eating close to the start of a long ride is my way of kind of forcing myself to pace myself for the first half of the ride. If you are doing a long ride in the morning you should definitely eat before the ride! Each person is different, though; I have a very high metabolism, especially since I'm riding so much right now and basically I have to eat all the time (like every two to three hours).
Are you on a special diet? Why do you take MCT powder?